The increasing popularity of smartphones and the increasing number of features of such phones has led to the incorporation of navigation assisting features in these devices. In addition to the proliferation of such smartphones, the popularity of personal (or portable) navigation devices has also increased. This proliferation of such portable navigation devices has led to cheaper and cheaper devices, with cheaper and cheaper components.
Estimating the orientation of a Portable Navigation Device (PND) is commonly achieved using onboard inertial sensors, i.e. rate gyroscopes and accelerometers. When these sensors are of low cost consumer grade, they suffer from time varying errors that require specific mitigation methods.
Global Navigation Satellite System (GNSS) is often the most effective technology to compensate for sensor errors. However this approach is only effectively feasible if the GNSS signals are not degraded by environmental and man-made factors. Because pedestrian navigation based on PND occurs mainly in signal degraded environments such as inside buildings and along city streets, it is not feasible to rely only on GNSS technology to estimate the sensor errors. Man-made electronic interference caused by wireless devices operating near GNSS frequencies can also adversely affect signal acquisition and tracking, both outdoor and indoor. Interference sources include anti-spoofing and intentional and unintentional jamming. Complementary techniques consist in taking advantage of a specific known IMU location on the pedestrian's body to mitigate the IMU sensor errors. For example when the IMU is located on the foot, it is possible to constrain the velocity of the navigation solution during the stance phase leading to the estimation of inertial sensor errors. When the Inertial Measurement Unit (IMU) location is not body fixed, i.e. not rigidly attached to the pedestrian's body, as in the case of a mobile phone for example, there exists no similar technique to constrain the error growth in the navigation solution. In PND-based navigation applications, the IMU location is generally not fixed to the body but is in a hand, a side pocket, a purse etc, which leads to alternative error mitigation methods.
Based on the above, there is therefore a need for systems and methods which mitigate the issues presented above and which address the same issues.